91% of Great Barrier Reef bleached

Sydney – A prolonged summer heatwave in Australia left 91% of the Great Barrier Reef’s coral damaged by bleaching, according to a new government monitoring report.

It was the first time on record the reef had suffered bleaching during a La Nina weather cycle, when temperatures would normally be expected to be cooler.

The Reef Snapshot report offered new detail on the damage caused by the fourth “mass bleaching” the world’s largest coral reef system has experienced since 2016.

The Great Barrier Reef Marine Park Authority conducted extensive surveys of the World Heritage-listed reef between September last year and March this year.

It found that after waters began to warm last December, all three major regions of the reef experienced bleaching, which occurs when coral is stressed and expels brightly coloured algae living in it.

Although bleached corals are still alive and moderately affected sections of the reef may recover, “severely bleached corals have higher mortality rates”, the report said.

Of the 719 reefs surveyed, the report said 654 – or 91% – showed some level of coral bleaching. –